Abstract: The invention relates to an image detector for a camera operating in a "day" mode and a "night" mode. The detector comprises an evacuated envelope containing a semitransparent photocathode for the transmission of incident photons or for converting photons into photoelectrons, depending on whether the mode is "day" or "night", respectively. The detector also comprises a detector capable of converting the incident photons or the photoelectrons into an electrical image signal. The image detector further includes electronic means for focussing the photoelectrons onto the detector, and optical means for focussing the photons onto the photocathode or onto the detector. The photocathode comprises a thin layer having at least one active layer of a III-V n-type material. The detector consists of a two-dimensional charge transfer device. The electronic means for focussing the photoelectrons on the charge transfer device comprises proximity focussing means.